Melting, Evaporation and Sublimation Processes in Ultra-High Precision Processing

本研究旨在了解能量束加工中的高速和微小现象，并了解实现更高精度所需的主导因素。主要研究结果如下：电火花加工中的传热首先，通过反问题求解得到进入电极的能量分布，发现进入阳极的能量大于进入阴极的能量。然而，阳极的材料去除率高于阴极。这是因为碳在阳极表面的沉淀可以保护阳极免受磨损。其次，采用有限差分法计算了脉冲放电产生的等离子体在脉冲间隔内去离子和恢复放电间隙的介电击穿强度所需的时间，并将计算结果与实验结果进行了比较。研究发现，当采用低热扩散系数的材料作为电极时，等离子体去离子所需的时间较长，过程容易变得不稳定。采用实验和数值方法研究了激光辐照聚合物薄膜中凹坑的形成过程。实验中使用了半导体激光器、氩激光器、准分子激光器和四次谐波YAG激光器来考察光束波长的影响。在半导体激光和氩气激光引起的热过程中，聚合物薄膜的辐射热流密度和吸收系数的增加促进了凹坑的形成。在有限元数值分析中，梁吸收模型和梁强度分布的影响通过马兰戈尼力的作用影响基坑表面变形。在准分子激光和YAG激光引起的非热过程中，辐照的紫外光束引起激光烧蚀过程。在这种情况下，去除体积与辐照能量呈线性关系。凹坑表面形貌与材料、拉伸历史和辐照条件有关。少

This study aimed to understand the high-speed and minute phenomena in energy beam machining and to know the dominating factors needed to attain the higher precision. The followings are the main results :Heat transfer in electrical discharge machiningFirst, the energy distribution into electrodes was obtained from the inverse problem solution, and it was found that the energy distribution into the anode is greater than that into the cathode. However, the material removal rate of the anode is higher than that of the cathode. This is because the precipitation of carbon onto the anode surface protects the anode from wear. Secondly, the time required to deionize the plasma generated by a pulse discharge and recover the dielectric breakdown strength of the discharge gap during the pulse interval was calculated by the finite difference method, and the calculated results were compared with the experimental results. It was found that when materials with low thermal diffusivity are used as the e … More lectrodes, the time required to deionized the plasma is long and so that the process is likely to get unstable.Pit formation process in a polymer film by laser irradiationPit formation process was investigated both experimentally and numerically. In the experiments, various lasers, which were semiconductor, argon, excimer, and fourth harmonic YAG lasers, were used in order to examine the effect of the beam wavelength. In the thermal process caused by the semiconductor laser and the argon laser, the increase in irradiated heat flux and an absorption coefficient of the polymer film promoted the pit formation. In the numerical analysis using the finite element method, the effect of beam absorption model and beam intensity profile affected the pit surface deformation by the effect of the Marangoni force. In the non-thermal process caused by the excimer laser and the YAG laser, irradiated ultra-violet beam caused laser ablation process. For this case, the removed volume and the irradiated energy showed linear relation. The pit surface morphology showed the dependency on a material, tensile history, and an irradiation condition. Less